Back to EveryPatent.com
United States Patent |
5,292,401
|
Yoneda
|
March 8, 1994
|
Method of forming a fine pattern
Abstract
A fine pattern forming apparatus includes a stage and an opposed electrode
at least one of which is made of a magnetic material. A magnetic field is
applied to this stage or opposed electrode to provide a predetermined gap
between the stage and the opposed electrode for a fine pattern formation.
In consequence, optimum etching conditions (including etching uniformity,
etch rate and etching direction) can be assured without generating dust.
As a result, damage caused by the plasma can be reduced, and the etch rate
can be increased.
Inventors:
|
Yoneda; Masahiro (Itami, JP)
|
Assignee:
|
Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP)
|
Appl. No.:
|
044009 |
Filed:
|
April 8, 1993 |
Foreign Application Priority Data
Current U.S. Class: |
216/67; 118/723E; 118/728; 204/192.32; 204/298.15 |
Intern'l Class: |
H01L 021/00 |
Field of Search: |
156/643,345
118/723,728,729
204/192.13,192.32,298.15
|
References Cited
U.S. Patent Documents
4351805 | Sep., 1982 | Reisman et al. | 422/202.
|
4563240 | Jan., 1986 | Shibata et al. | 156/643.
|
Foreign Patent Documents |
0132538 | Feb., 1985 | EP.
| |
3914065 | Oct., 1990 | DE.
| |
3935189 | May., 1991 | DE.
| |
4-128780 | Mar., 1992 | DE.
| |
4128779 | Mar., 1992 | DE.
| |
58-17018 | Feb., 1983 | JP.
| |
59-94422 | May., 1984 | JP.
| |
60-62460 | Apr., 1985 | JP.
| |
60-195938 | Oct., 1985 | JP.
| |
61-87884 | May., 1986 | JP.
| |
61-227169 | Oct., 1986 | JP.
| |
65-57214 | Mar., 1987 | JP.
| |
63-219137 | Sep., 1988 | JP.
| |
1-107539 | Apr., 1989 | JP.
| |
1-279783 | Nov., 1989 | JP.
| |
2-229442 | Sep., 1990 | JP.
| |
Other References
Yoneda et al, "Anisotropic Etching of Poly-Si By RIE", Dry Process
Symposium, 1981, pp. 47-53.
|
Primary Examiner: Hearn; Brian E.
Assistant Examiner: Goudreau; George
Attorney, Agent or Firm: Leydig, Voit & Mayer
Parent Case Text
This application is a division of application Ser. No. 07/865,648, filed
Apr. 10, 1992, now U.S. Pat. No. 5,228,940 which is a continuation of
application Ser. No. 07/644,574, filed Jan. 23, 1991.
Claims
What is claimed is:
1. A fine pattern forming method comprising the steps of:
placing a sample on which a fine pattern is to be formed on a stage in a
vacuum chamber;
evacuating the interior of said vacuum chamber to achieve a predetermined
degree of vacuum;
supplying a reactive gas into said vacuum chamber;
applying a magnetic field to levitate one of said stage and an opposed
electrode located in said vacuum chamber to maintain a predetermined gap
between said stage and said opposed electrode; and
generating a plasma of said reactive gas within said vacuum chamber by said
stage and said opposed electrode, thereby forming a fine pattern in said
sample.
2. A fine pattern forming method according to claim 1 wherein said fine
pattern forming method is a plasma etching method.
3. A fine pattern forming method according to claim 1 wherein said fine
pattern forming method is a reactive ion etching method.
4. A fine pattern forming method according to claim 1 wherein said fine
pattern forming method is a magnetic field supported reactive ion etching
method.
5. A fine pattern forming method according to claim 1 wherein said fine
pattern forming method is a electron cyclotron plasma etching method.
6. A fine pattern forming method according to claim 1 wherein said fine
pattern forming method is a neutral beam etching method.
7. A fine pattern forming method according to claim 1 wherein said fine
pattern forming method is a light excited etching method.
8. A fine pattern forming method according to claim 1, wherein said fine
pattern forming method is a light supported etching method.
9. A fine pattern forming method according to claim 1 wherein said fine
pattern forming method is a sputter etching method.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fine pattern forming apparatus for
forming a fine pattern on a substrate or in a thin film formed on the
substrate, and a method of forming the fine pattern.
2. Description of the Related Art
FIG. 1 is a schematic cross-sectional view of a conventional fine pattern
forming apparatus, e.g., a plasma etching apparatus. In this apparatus, a
semiconductor substrate 2, in which a fine pattern is to be formed, is
disposed within a vacuum chamber 1. The semiconductor substrate 2 may be
one which has on its surface a polycrystal-line silicon thin film and on
the polycrystal-line silicon thin film a photoresist pattern serving as a
mask which resists etching. In the vacuum chamber 1, the semiconductor
substrate 2 is placed on a stage 4 which also serves as an electrode
connected to a high-frequency power source 3 for supplying high-frequency
power. An opposed electrode 6 with gas nozzles 5 provided therein to
uniformly supply an etching gas which is a reactive gas, e.g., chlorine
gas, toward the semiconductor substrate 2 is disposed in opposed relation
to the semiconductor substrate 2. The vacuum chamber 1 is provided with an
evacuation port 7 through which the vacuum chamber 1 is evacuated as well
as a reactive gas supply port (not shown) through which the etching gas is
supplied into the vacuum chamber 1. An opposed electrode 6 moving means 8
made of, for example, a screw is provided on the portion of the vacuum
chamber 1 on which the opposed electrode 6 is mounted so as to provide a
predetermined gap between the opposed electrode 6 and the stage 4.
The thus-arranged conventional fine pattern forming apparatus will be
operated in the manner described below. First, an etching gas is
introduced into the interior of the vacuum chamber 1 from the reactive gas
supply port (not shown) through the gas nozzles 5 while the vacuum chamber
1 is evacuated from the evacuation port 7 by an evacuation means (not
shown). Next, a high-frequency voltage is applied between the stage 4 and
the opposed electrode 6 by the high-frequency power source 3 to generate a
glow discharge, by means of which the etching gas introduced into the
vacuum chamber 1 is activated and a plasma A is generated, thereby
producing active neutral molecules, neutral atoms and ions. Etching of the
semiconductor substrate 2 progresses due to the presence of these
molecules, atoms and ions, and a fine pattern is thus formed.
The above conventional fine pattern forming techniques has the following
drawbacks.
(1) Uniformity of the etch rate
In the conventional techniques, since the gap between the electrodes is
fixed or changed mechanically, it is difficult to provide an optimum
electrode gap which greatly affects uniformity of the etching.
Furthermore, since spatial distribution of the activated halogen gas or
ions occurs, when a fine pattern is to be formed on a sample having a
large diameter, a non-uniform distribution of the etch rate across the
diameter occurs. A reduction in the etch rate requires a large etching
chamber.
(2) In the conventional techniques, since the stage 4 can be moved only
mechanically, generation of dust caused by the movement cannot be
eliminated. In consequence the performance of the apparatus is reduced,
and the interior of the chamber 1 must be cleaned frequently. In
particular, by-products of the etching gas, which may would be the cause
of generation of dust by themselves, adhere to the moving means 8 for the
opposed electrode 6 and peel off from the moving means 8 when the
semiconductor substrate 2 is placed on or removed from the stage 4,
generating dust.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a fine
pattern forming apparatus which eliminates dust generation and in which
the electrode gap can be changed without contact to ensure excellent fine
pattern forming characteristics in the fine pattern formation conducted on
various materials by various fine pattern forming methods.
In order to achieve the above object, according to one aspect of the
present invention there is provided a fine pattern forming apparatus which
comprises: a vacuum chamber; reactive gas supplying means for supplying a
reactive gas into the vacuum chamber; a stage disposed within the vacuum
chamber for supporting a sample thereon and serving as an electrode, at
least part of the stage being made of a magnetic material; an opposed
electrode provided in opposed relation to the stage on which the sample is
placed; magnetic field generating means for levitating the stage
magnetically to provide a predetermined gap between the stage and the
opposed electrode; and evacuation means for evacuating the interior of the
vacuum chamber.
According to another aspect of the present invention, there is provided a
fine pattern forming apparatus which comprises: a vacuum chamber; a
reactive gas supplying means for supplying a reactive gas into the vacuum
chamber; a stage disposed within the vacuum chamber, the stage for
supporting a sample and serving as an electrode; an opposed electrode
provided in opposed relation to the stage, at least part of the opposed
electrode being made for generating a magnetic material; a magnetic field
generating means for generating a magnetic field for levitations the
opposed electrode magnetically provide a predetermined gap between the
stage and the opposed electrode; and evacuation means for evacuating the
interior of the vacuum chamber.
According to still another aspect of the present invention, there is
provided a fine pattern forming method which comprises the steps of:
placing a sample on which a fine pattern is to be formed on a stage in a
vacuum chamber; evacuating the interior of the vacuum chamber to achieve a
predetermined degree of vacuum; supplying a reactive gas into the vacuum
chamber; applying a magnetic field to levitate one of the stage and an
opposed electrode magnetically relation to the stage by a magnetic field
generating means to make the stage or the opposed electrode magnetically
and thereby maintain a predetermined gap between the stage and the opposed
electrode; and generating a plasma of the reactive gas within the vacuum
chamber by the stage and the opposed electrode and thereby forming a fine
pattern in the sample.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view of a conventional plasma etching
apparatus;
FIG. 2 is a schematic cross-sectional view of a first embodiment of the
plasma etching apparatus according to the present invention; and
FIG. 3 is a schematic cross-sectional view of another embodiment of the
plasma etching apparatus according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 2 is a schematic view of a first embodiment of a fine pattern forming
apparatus, e.g., a plasma etching apparatus according to the present
invention. In FIG. 2, reference numerals 1 to 3, 5 and 7 respectively
denote parts which are the same as those of the conventional fine pattern
forming apparatus shown in FIG. 1. In the plasma etching apparatus shown
in FIG. 2, a magnetic body 9 is embedded in a stage 4A on which the
semiconductor substate 2 is placed. The stage 4A also serves as an
electrode. An external magnetic field coil 10 which is a magnetic field
generating means is disposed outside of the vacuum chamber 1 to levitate
the stage 4A magnetically due to the magnetic field generated by the
external magnetic field coil 10. The stage 4A is connected to the
high-frequency power source 3 via a flexible electric wire 11 or the like.
In the fine pattern forming method which employs the above-described fine
pattern forming apparatus, first, the semiconductor substrate 2 is placed
on the electrode 4. Next, an etching gas which is a reactive gas is
introduced into the vacuum chamber 1 from a reactive gas supply port 12
through the gas nozzles 5 while the vacuum chamber 1 is evacuated from the
evacuation port 7. A high-frequency voltage is then applied between the
stage 4A and the electrode 6 by the high-frequency power source 3 so as to
generate a glow discharge. In consequence, the etching gas introduced into
the vacuum chamber 1 is activated and a plasma is thereby generated,
generating active neutral molecules, neutral atoms and ions. Etching of
the semiconductor substrate 2 progresses due to the presence of these
molecules, atoms and ions, and a fine pattern is thus formed.
At that time, a magnetic field is generated by the external magnetic field
coil 10 so as to provide a predetermined gap between the opposed electrode
6 and the stage 4A on which the semiconductor substrate 2 is placed due to
the repelling force of the magnetic field. When an optimum electrode gap
is maintained, the etching characteristics can be improved. Furthermore,
the magnitude of the electric field in ion sheaths formed around the
electrodes is reduced by the action of the magnetic field generated by the
magnetic body 9 buried in the stage 4A, and the colliding energy of the
ions can thus be reduced, thereby reducing damage to the substrate
processed by the plasma during the process. Furthermore, the density of
the ions in the plasma increases due to the magnetic field, thereby
increasing the etch rate.
In the above-described embodiment, the stage 4A is made to magnetically
float. However, as shown in FIG. 3, whereas the stage 4 is fixed, an
opposed electrode 6A may be made of, for example, a ferromagnetic material
so that it can be made to magnetically float in order to provide an
optimum electrode gap. In that case, the reactive gas supply port 12 and
the opposed electrode 6A are connected to each other by a flexible pipe 13
or the like.
The above-described embodiment employs as the fine pattern forming method
the plasma etching process. However, the present invention is also
applicable to the reactive ion etching process, the magnetic field
supported reactive ion etching process, the electron cyclotron plasma
etching process, the neutral beam etching process, the light excited
etching process, the light supported etching process or the physical ion
etching process.
The semiconductor substrate 2 with a polycrystal-line silicon thin film
formed thereon is used as a film on which a fine pattern is to be formed.
However, a silicon oxide film, a silicon nitride film or a silicon
oxynitride film may also be used. A single crystal silicon film may also
be used.
Furthermore, the film in which a fine pattern is formed may be made of
tungsten, tantalum, molybdenum, zirconium, titanium, hafnium, chromium,
platinum, iron, zinc, tin, a silicide of any of these substances, a
nitride of any of these substances or a carbide of any of these
substances; aluminum, copper, gold, silver or an alloy which is mainly
composed of any of these metals; or an organic polymer such as a novolak
resin or polyimide.
Furthermore, the film in which a fine pattern is formed may be a
ferroelectric material such as PZT, (lead, zinc, tin), a superconductor
including an oxide superconductor or a ferromagnetic material.
The above embodiment employs as a sample, i.e. a substance, to be
processed, the thin film formed on the semiconductor substrate 2 in the
semiconductor integrated circuit manufacturing process. However, the
present invention is also applicable to a substrate of a magnetic tape or
of a magnetic disk employed in magnetic storage apparatus which is
subjected to a storage device forming process, a substrate for an optical
disk or the like employed in optical storage apparatus which is subjected
to a storage device forming process, a metal shaped substance, a thin film
formed on the surface of the metal shaped substance, a machine component
such as a screw or a machining tool.
As will be understood from the foregoing description, in the fine pattern
forming apparatus and method according to the present invention, since the
stage on which the sample is placed or the opposed electrode is made to
magnetically levitate and is thereby moved without contact to adjust the
electrode gap, optimum etching conditions (including etching uniformity,
etch rate and etching direction) can be assured without generating dust.
In consequence, damage caused by the plasma can be reduced, and the etch
rate can be increased. These enable excellent fine pattern formation.
Top